1. Field of the Invention
The present invention relates to a shearing machine having a pair of upper and lower shearing blades for cutting or shearing sheet-like materials such as sheet metals.
2. Description of the Prior Art
As is well-known, the shearing machine for shearing sheet-like materials such as sheet metals comprises a pair of opposite upright plates, a pair of elongated upper and lower shearing blades and a work-table on which a work-sheet is fed and held to be sheared. The lower blade is horizontally fixed to the work-table, and the upper blade is held by a ram which is disposed to move up and down between the upright plates to move the upper blade toward and away from the lower blade. Also, a plurality of hold-down means of hydraulic or pneumatic cylinders are provided at the front portion of the shearing machine for holding the work-sheet to be sheared on the work-table, and furthermore a back gauge means is provided to set the widths or lengths into which the work sheet is to be sheared.
Another problem with regard to the conventional shearing machine has been that the hydraulic or pneumatic hold-down means for holding the work-sheets to be sheared will virtually strike the work-sheets onto the work-table, since high pressure is abruptly urged in the hold-down means. Therefore, it has been very disadvantageous that tremendous noises will be produced when the work-sheets are being held by the hold-down means and furthermore the work-sheets will be damaged by the hold-down means.
Another disadvantage with the conventional shearing machine has been that the work-sheets, which are wide and long, will bend and curl to become undesirable shapes, since they cannot be perfectly held when being sheared.
It has been further disadvantageous with regard to the conventional shearing machine that the back gauge means will be in the way when a work-sheet is to be sheared into an irregular size without need of the back gauge means while other work-sheets are being continuously sheared into a certain size.